


The Zero Contagion

by HalfBakedPoet



Series: One Shot, Two Shot, Some Shots, Blue Box [8]
Category: Doctor Who (2005)
Genre: Action/Adventure, Adventure & Romance, Angst, F/F, Illnesses, Long One Shot, One Shot, Quarantine, Requested by anon, Some Fluff, Still feral writing, buckle up for hurtsville beep beep, coronapocalypse posting, thasmin
Language: English
Status: Completed
Published: 2020-03-23
Updated: 2020-03-23
Packaged: 2021-02-28 20:41:25
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 5,831
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23273386
Author URL: https://archiveofourown.org/users/HalfBakedPoet/pseuds/HalfBakedPoet
Summary: “That’ll be your immune system,” said the Doctor. Fast-acting alien virus attacking Yaz’s body, her white blood cells would be off the charts, swarming, parasympathetic nervous system kicking in with inflammation. “Fighting the good fight. Best you rest.”Yaz catches an incurable disease and the Doctor races to cure it. Angst ensues.
Relationships: The Doctor/Yasmin Khan, Thirteenth Doctor/Yasmin Khan
Series: One Shot, Two Shot, Some Shots, Blue Box [8]
Series URL: https://archiveofourown.org/series/1668127
Comments: 25
Kudos: 56





	The Zero Contagion

**Author's Note:**

> Requested by an anonymous friend, prompt: "Quarantine"
> 
> TW for death mentions, proceed at your own leisure.

The Doctor poked her head out of the TARDIS door. An open air market draped in bright orange and deep pink fabrics bustled around her. Hundreds of aliens bore baskets stall to stall; some humanoid bipeds, others many more multipedal, some scaled, some feathered, species of all colors, selecting delicacies and trinkets, haggling for fair and unfair prices. A whorl of sizzling meat rubbed in spices from across the stars wafted from a vendor grilling all sorts of cuts and fish two stalls down. Sparing the briefest smile for the chaotic, living rainbow hurrying around her ship, the Doctor looked back over her shoulder at Yaz and nodded her over for a look. Yaz, too, peeked out the front door, head over the Doctor’s in the small gap to the outside, hand resting on her shoulder.

“It’s _beautiful_ ,” said Yaz, eyes widening with wonder. The Doctor’s ears warmed; she could hear Yaz grinning when she spoke. “Can we have a look around?” she begged.

And the Doctor’s stomach dropped to her boots: whatever the TARDIS had brought them here for, it would be difficult to find at best. In the vortex between space and time, a shift in direction rocked the Doctor and Yaz out of their seats, sloshing tea everywhere, and the TARDIS scanners started flashing red, reading _HIGH HAZARD, DOCTOR NEEDED_ over and over before she materialized in the middle of this market. Reaching out the door first with her sonic, the Doctor gave the area a general scan. From the fashion of the locale, she judged eighty-first century on the planet Alpha-Seventeen, which a local confirmed when she asked. The sonic turned up nothing unusual; no trace of exotic weaponry or any of the usual suspects: no Daleks, Cybermen, Zygons or the like. No Pting, either.

“All right, just a quick look,” she said. From a deeper coat pocket, she gave Yaz a handful of coins, glass beads, buttons, loose crystals, some bits of yarn, a lone stone marble, and individually wrapped boiled sweets. “Good barter material,” she assured with a wink, to Yaz’s amusement. The Doctor proceeded first out the door, taking each step gingerly, Yaz at her heels. Another scan, another report of nothing unusual. Arms wide in confused exasperation, she let them drop to her sides, her brow furrowed. “What did you bring us here for if there isn’t anything out of the ordinary?” she shouted back at the TARDIS, her voice lost in the crowd. The TARDIS lantern blinked at her once: _Here, it’s here._

 _Ought to tie a string around Yaz_ , she thought, as the crowd carried Yaz along to a stall with handcrafted ceramic wares, iridescent glaze shimmering. Elbowing through to Yaz, she said in her ear, “Stick close, keep a sharp eye.” Yaz nodded that she understood, and politely admired the large bowl the toad-like shopkeeper held up for her to see. It was a lovely market, the Doctor admitted, still on edge as they traded two of the sweets for kebabs. Anxiety trilled in the Doctor’s chest as Yaz drifted away and back, so, in the crush of bodies, catching up to her for what seemed like the thirty-fifth time, the Doctor firmly took hold of her hand.

This made Yaz jump, but, blushing, she turned to beam at the Doctor. “Oh, look!” she pointed at a stall of what the Doctor recognized as various instruments carved from wood and stone, some stringed and others most similar to a many-pronged Earth flute. A simple guitar stood out most to the Doctor and, exclaiming, she scooped it up.

“Oh, I love a guitar! I’m not very good yet,” she admitted to the curious vendor, throwing the woven strap over her shoulder. Yaz covered her face. The Doctor set her fingers to the strings and struck a wonky chord. The guitar could have been whining as she shrilled over the frets. “Wait, that’s not it.” She adjusted down the neck. “Mostly self-taught, YouTube only goes so far,” she said, smiling apologetically to the owner, who was trying not to plug her ears. “It’s a lovely instrument. How much?” The vendor, trying to hide her grimace as a smile, but not going to turn down a sale, pointed to the crystals in Yaz’s palm. “Brilliant,” said the Doctor, handing them over and slinging the guitar against her back. She turned to Yaz, who did her best to look approving, and said, “Best get back to the TARDIS and come back when it’s not so crowded. Might get a better read when there isn’t so much hustle on.” She took Yaz’s hand again.

Yaz agreed and they had just stepped back into the throng when a frantic yell pierced the air: “Out of the way! Get out of—MOVE!” Like a jacket unzipping, the crowd parted to either side of the aisle of stalls, upsetting stands and displays as a single humanoid male dashed through with a loaf of bread under his arm, delicate gold chains and glimmering valuables dangling from his pockets. Yaz had turned away from the Doctor to see what was happening just in time for the runner to slam right into her, tearing her hand apart from the Doctor’s as they fell to the ground.

“What’re you doing, you stupid—” he started, beads of sweat dripping onto Yaz’s face, but the Doctor scruffed him by his jacket collar before he could say more.

“Oi, that’s my friend you just knocked over,” said the Doctor. “Where’re you off to in such a hurry, anyway?” She didn’t let him respond. “By the looks of it, you were trying to give those fellows over there the slip.” She raised her eyebrows at the local police in hazmat suits, who were hurrying toward them.

“No, you don’t understand,” the man started again, blue eyes bloodshot and wild. His short brown hair was stringy with sweat. Could do with a wash, this one, thought the Doctor. But the police had caught up before he could plead his case further.

“Officers, I seem to have caught your perpetrator, free of charge,” said the Doctor, happily transferring her grip on the fellow into their waiting arms. She helped Yaz up from the ground. “But what I haven’t worked out is, why the hazmat suits?” As the officers started to bundle the thief away, huddled around him, it dawned on her, her eyes widening, mouth starting to hang open. “No.” Quickly, she scanned his back. _Biohazard, avoid contact with all bodily fluids, highly contagious, transmission fast-acting._ Faster, she scanned herself. Negative, no contact with his skin or sweat. In mute horror, the Doctor turned to Yaz, who was wiping the man’s sweat and spittle from her face with her sleeve. She scanned Yaz, her entire body shaking. _Biohazard, avoid contact with all bodily fluids, highly contagious._

The Doctor staggered backward into a post, guitar clunking, her knees buckling. “ _No._ ”

Bewildered, Yaz said, “Doctor?” but didn’t get to say much more.

“You’re gonna have to come with us,” said a policewoman as her cohort escorted the man back the way he had run. Her voice was somewhat robotic as it filtered through a speaker on her face shield. And they found themselves surrounded by white hazmats, a traveling pod that ushered them along, sterile bodies between them and the crowd, who stood by to gawp.

“Yaz, I’m gonna need you to keep very, very calm and not touch anything,” said the Doctor in a low voice, desperately wishing she could give Yaz’s hand a comforting squeeze. After putting her hood up, she shoved her own hands in her pockets, staring hard at her feet as they shuffled along into a waiting medi-cruiser.

“I told you, I’m fine, he didn’t touch me,” said the Doctor an hour later in the confines of a medical pod scan. She had never liked medical procedures on Gallifrey or Tsuranga or any other location in the universe. Always too intrusive, poking with too many instruments.

She glanced over at Yaz through the glass, who was surrounded by aliens in scrubs and face masks. They swabbed inside her mouth, shone lights in her eyes, and took samples of her hair, bombarding her with questions all the while.

“Are you feeling anxious or dizzy? Are you experiencing bodily tremors or weeping rash?”

Yaz, more confused and upset than ever, though she was doing her best to put on a brave face, looked as though she was about to cry, and the Doctor rapped on the glass to get her technician’s attention. “Oi, if you’re done scanning me and finding exactly what I just told you, let me out of here so I can help my friend.” To her annoyance, the tech held up one of three fingers and _too_ slowly pressed a button on her control panel. Sanitizing steam gushed into the pod and the Doctor emerged, coughing. She ran as close as she could to Yaz before a nurse, placed herself between them.

“Yaz,” said the Doctor, craning over the nurse’s shoulder, desperate to think of something comforting to say, “It’s alright, you’ll be alright, you’ll be fine.” Yaz nodded tearfully as a nurse poked a thermometer into her mouth. The Doctor rounded on the person nearest to her with a clipboard. Clipboards meant someone was in charge, right? “Hello, mate,” she breezed, pulling the clipboard down so he would look at her, “Loads of questions, but first what are we being held here for and what’s going to happen to my friend?”

“You mean you don’t know?” said the tech, sliding a pen into his lab coat pocket. Out of everyone medical in the room, the Doctor and Yaz aside, he looked the most human and the Doctor recognized him as a Gifftan. “You got lucky you weren’t infected. Our Patient Zero made a break for it and was planning to skip the planet. Would have been disastrous if this virus got out into the galaxy.”

“What kind of virus are we talking?” the Doctor demanded, fishing in her pocket. “And why haven’t I heard of it?” She flashed the psychic paper in his face.

His eyes widened. “Intergalactic Surgeon General.”

The Doctor glanced at the paper, impressed for a blink, and replaced it in her pocket. “That’s right, I’m a doctor, just like you, now tell me what’s going on here or I’ll have your job and you’ll never work in hospital again.”

In a low voice, the tech said, “You’d best come with me somewhere private.” The Doctor looked back at Yaz, whose tears were now being bottled in tiny vials by the staff.

“Yaz, I’m coming back for you,” she said. “Hang tight, be brave. I’ll be right back.”

They settled into an office down the hall and he set his clipboard on what appeared to be his desk, which read _Zari Nordoss, I.M.D., I.D.E._ “I didn’t want to cause more of a panic back there, this is still a developing case. Please sit,” said Zari Nordoss, seating himself behind his name plate.

 _Intergalactic M.D., Infectious Diseases Expert_ , the Doctor registered. She did not sit down and opted to pace around the office like a caged animal, picking up books and putting them down again. “No wonder the TARDIS brought us here,” she said to herself. “You’re on the cusp of an epidemic, Zari. Alright if I call you Zari?”

“Doctor Nordoss, if you please. And indeed, we are,” he said. “This is unlike any virus I’ve ever seen. Every treatment we’ve tried on our Patient Zero, it’s like the virus knows how to fight back and purge it.” The Doctor had taken the framed degree off the wall and given it a lick. Just dust. She wiped her tongue on her sleeve.

“You’re talking sentient rogue DNA strands, Zari?” The Doctor leaned over the desk. “That can’t be possible.”

“So it would seem,” said Nordoss. He steepled his fingers and stared back, bags under his eyes. “Luckily, we found the first case before he could infect anyone else. The virus doesn’t last longer than five seconds outside a living host, so anything he touched in the market will be clean. Tricky to study, though. It’s like the virus dies when it realizes it can’t infect anything else.”

“Well a good job that no one else has caught it,” said the Doctor, turning to another bookshelf and setting an orbit of steel balls in motion on a fidget sculpture. “You’ll want to run a team back to check on the market as well. So, what happens to Yaz?”

Zari Nordoss turned his chair to the wide window behind him, sunlight beaming through to his face through the slats in the blinds, making shadow stripes. “We’ll have to quarantine her until there’s a cure,” he said finally. “You should go back to wherever it is you came from and thank your lucky stars you didn’t catch it.”

“Not gonna work, Zari,” said the Doctor, advancing toward him. “I don’t leave this planet without Yaz.”

He sighed. “Do as you will, but under no circumstances are you allowed to break the quarantine. We’ve put in a request for a reversed ionic membrane, so this doesn’t happen again.”

“Reversed ionic membrane? That’s clever, should’ve thought of that myself,” she said. “Keeps the virus from leaving here, well done.” And then she remembered that meant Yaz couldn’t leave, either. She asked again, “What happens to Yaz? I mean the virus, what will it do to her?”

“Patient Zero has exhibited some moderate disruptions to his internal organs, but he’s not human, so we… we don’t know,” he admitted.

The Doctor’s face darkened. “Brilliant,” she said sarcastically, “So all we can do is wait while Yaz becomes a test subject and a biohazard with an unknown virus that could very well kill her?”

“So it would seem,” said Zari. “We’re working on a cure, but testing could take month—”

“That’s not good enough!” shouted the Doctor. Her voice rang out and the office fell silent, and the only sound was her breathing, hard. She half composed herself, shaking. “Right. I’m going to need all access to your labs and equipment. And a place to park my TARDIS.”

“Here you are, Yaz,” said the Doctor cheerfully through the glass of Yaz’s room, though her heart sank to see Yaz so isolated. Through the small window, she slid a stack of books and puzzles with a custard cream on top. Yaz had been permitted to wear her own clothes, and the Doctor had transferred a portion of her wardrobe already, which lay folded in a corner near the white-covered bed. “Do you want a poster or flowers or something to brighten up the place?”

“That’s alright, Doctor, thanks,” said Yaz, quiet and pale. “The TARDIS brightens it up plenty.” And indeed, the Doctor had parked right outside Yaz’s glass chamber, leaving the doors wide open so she could scurry back and forth, depositing essentials to Yaz through her window. The TARDIS herself murmured worry, making more anxious beeps than usual. _Good thing she can’t understand you, mate. Don’t want to worry her more._ “You’d think I’d be used to weird by now,” said Yaz, sitting on the end of her bed. “Did your other friends catch unknown alien diseases so suddenly?”

“Once or twice,” said the Doctor, adding quickly, “But they got better.” Yaz nodded. “How’re you feeling?”

“Weak,” said Yaz. “Shaky.” Her breath rattled and the Doctor forced her face to remain on the neutral side of concern.

“They ran you through the gamut of tests, didn’t they?”

“They did,” said Yaz. “Blood, saliva, urine, reflexes, all of it. They said other than being infected, I’m healthy, but I’m not so sure, ‘cause I feel off.” She frowned. “Maybe it’s just psychological. I know I’m ill, so I feel worse?”

“That’ll be your immune system,” said the Doctor. Fast-acting alien virus attacking Yaz’s body, her white blood cells would be off the charts, swarming, parasympathetic nervous system kicking in with inflammation. “Fighting the good fight. Best you rest.” The Doctor pressed her palm against the glass and Yaz, fighting more tears, held her own hand up to it. “Keep fighting, Yaz’s immune system. I’ll get this sorted, don’t you worry.”

The Doctor ransacked the lab next, waving her psychic paper about as she pocketed vials of Yaz’s samples and peered into microscopes. “Intergalactic Surgeon General coming through. Here to lend a hand, budge up, let’s get a shift on.” She herded staff toward different tables, examined screens, and thumbed through files, rapidly throwing papers over her shoulder as she finished reading them. Just as she was scanning a vial with her sonic, magnifying goggles on, Doctor Nordoss arrived to see the chaotic state of the lab: papers strewn about, overturned chairs, and a few bewildered nurses in hazmat gear backed against a corner; the Doctor, the epicenter of it all.

“Doctor, when I said you could have access to the labs, I didn’t mean destroy them,” he said, righting a chair. “Do you have any idea what time of night it is?” he added, pointing at the clock, which read well into the wee hours.

“You’re right, though Zari, the virus in these saliva samples seems to have… self-destructed. Nothing left but a few scraps of DNA remaining and… is that a silicon nanochip fragment?”

“I don’t know what you’re—”

“It is!” said the Doctor, peering back and forth between the sonic and the sample. “Were Patient Zero’s samples like these?”

“That’s classif—” started Nordoss.

“Can I talk to him?” interrupted the Doctor. “Get another live sample for a quick look?”

“Due to patient confidentiality constrains—”

“Oh, hang confidentiality, Zari, I’ve already met him,” said the Doctor.

Nordoss struggled to answer, finally landing on, “That won’t be necessary, Doctor. Different species, different results for the virus.”

“But still, anything could help,” she insisted, scanning another sample. A whisper of thought started tickling the side of her head. “Hang on, there’s something…” She tilted her head to the right and screwed up her eyes, and the thought spoke louder, clearer: “A couple hours ago, you said you didn’t know if the virus would have other effects on different species. Now you’re telling me for certain there are different results. How do you know that without getting a living sample of it?”

Nordoss crossed his arms. “I think you should leave this lab before you destroy any more of our research,” he said stiffly. He was a good bit taller than the Doctor, but still she closed the distance between them to glare up at him, noses inches away. His eyes were a deep brown, pupils dilated. Miniscule beads of sweat peppered his upper lip.

“What’re you hiding, then, Zari? What skeletons you got in your closet you won’t let me have a look?” asked the Doctor in a low, silkily threatening voice.

“Leave this lab before I have you thrown out,” said Nordoss, nostrils flaring.

“Fine,” said the Doctor, “but know if I find anything out of place, any mistakes or ethical quandaries, I’ll have this place shut down. And if Yaz doesn’t get better, it’s on your head.”

She set up camp at the TARDIS console, shouting over to Yaz every so often to check on her. Not that the Doctor would have told her, but Yaz was looking peakier by the hour, her cheeks already starting to hollow out, her skin paling. The TARDIS ran a full analysis of the self-destructed virus bits and confirmed the presence of the silicon nanochip in the remains.

“Nordoss isn’t telling me something big,” said the Doctor softly, as Yaz had fallen asleep. She scowled as the TARDIS chirped back. “Yes, yes, I _know_ you’re doing your best and more intel would be helpful, but it’s what we’ve got for now. Don’t forget _I’m_ doing my best here, too.” The TARDIS made a humming noise. “Don’t you start with me, you brought us here,” snapped the Doctor. “We’re not losing Yaz like this, not now, not ever.”

When Yaz awoke an hour later, the Doctor slid a bowl of soup through her window. “Let’s get some food in you, Yaz, that’s it. Instant ramen, best there is for when you’re ill.” Yaz managed a small smile and, trembling, drank. The Doctor gave Yaz another scan through the glass. “At least we can manage your low blood sugar,” she muttered, grimly reading the output. _Cardiovascular and respiratory systems weakened. Renal structures weakened. Digestive tract weakened. Nervous system normal._ She ticked down the list of various organ systems and structures that made up Yasmin Khan, and over half had been compromised. Her brave, sturdy Yasmin Khan, soldiering on with her body already going to pieces.

“Listen, Yaz, I’ll be back soon. I need to find our thief from yesterday morning. Stay awake for a bit if you can.” She laid a quick kiss on the glass and dashed out.

A sonic to a map monitor in the hall (“You are here,” it said in a cheery, helpful voice, a blinking red dot on the map), and she located a staff locker room nearby. She picked the lock and slipped inside, tearing through locker after locker until she found a long white lab coat and surgical mask. Nowhere near as comfortable or fashionable as her own coat, which she’d left on the console of the TARDIS before she closed the doors, but it would do. With a slight sting, the surgical mask snapped on around her ears, and she was out in the hallway again with a breakfast trolley, as though she did this every day.

“Come on, come on,” she muttered, sonic behind her back as she stood casually facing the android-manned desk, hacking the map monitor for signs of Patient Zero. The sonic blipped, and a room on the map flashed once in green. “Got you.”

His door was locked, but again, that was an easy task. The Doctor edged into the room and locked the door behind her. Patient Zero was bouncing a red rubber ball against his own glass wall, looking bored. With a sigh of relief, the Doctor pulled the mask off her mouth and nose, and he looked up at her. “It’s you. From before.”

“That’s right. You still haven’t apologized for running into my friend and infecting her with your virus, but, bygones,” said the Doctor, words blurring together with speed. “You can still help.”

“That’s all I’m here for,” he said.

“You got a name, Patient Zero?” She chewed the syllables of his moniker as she spoke them.

“Funny,” he said and bounced the ball against the floor to the wall, and it returned to his hand.

“Funny? That’s your name? Your name’s _Funny?”_ The Doctor’s nose rumpled with confusion, mouth hanging open.

“No, funny they call me Patient Zero, where there are probably hundreds like me,” he said. “That and my name before they got me was actually Zero.”

“There’s more than you and Yaz with this virus, Zero?” asked the Doctor, scanning him again. His vitals read similarly to Yaz, though in increased states of breakdown. His nervous system was going past _weakened_ to _potentially compromised_.

“Nordoss tell you I’m the only other one?” He bounced the ball again, which was starting to annoy the Doctor.

“Zero, I want to help,” said the Doctor, and her mouth flattened into a line. “My friend is in a state like yours and she won’t last as long as you seem to have. Won’t be running through any marketplaces making a break for it.”

“You’d run, too, if you’d been through what I have,” said Zero.

“Tell me. Please,” she said. “We don’t have much time left.”

“You sure you can trust the word of a criminal?” Zero smiled to himself and threw the ball.

“More than I trust Nordoss and I know he’s hiding something.”

Zero stood from the bed and spoke so close to the glass, his breath condensed on it. He said in a low voice, “I was doing my time in Stormcage when he came ‘round. Bartered with the guards, paid ‘em well off to look the other way while he smuggled me and another out. Said we were going to change the world and I thought couldn’t be worse than there.” He coughed. “I was wrong.”

“What happened?”

“He said the government on Alpha-Seventeen had paid him to do bioresearch. It was half a lie, he _had_ been paid, but by an intergalactic mob boss to make bioweapons. Like this virus. He picked me because my species adapts to any threats it perceives, down to our cells. I was a puzzle he wanted to solve; he wanted to break me.”

“So that’s why the nanochip,” said the Doctor, her brain clicking along with Zero’s story. “He programmed this artificially intelligent… _supervirus_ to be as adaptable as you and he’s sitting back watching the warfare in your body, thinking about his payoff. Micro-nanotech _spliced_ onto bits of roaming DNA.” She ground her knuckles into her forehead.

Zero grinned. “Bingo. And when anyone tries to get a trace on a sample to cure it…” he spread his fingers and made an explosive sound. “The virus self-destructs.”

“And Yaz is human, her body can’t keep up with a virus programmed to challenge _your_ immune system,” said the Doctor quickly, starting to panic.

“You should have seen the other guy,” said Zero, “He must’ve been made of softer stuff than humans because he lasted less than a day before everything in his body just shut down. Reckon your friend is going for the same fate come tomorrow.”

The Doctor was already darting for the door, but paused to say a sincere, “Thank you, Zero,” before running back to Yaz.

_Got to get a_ living _sample,_ she thought, sprinting back to Yaz’s room. “Yaz! I need you to come to the wind—” She burst through the door and stopped dead in her tracks. Yaz lay, limp as a rag doll, on the floor. “Oh no, nonono _no_ ,” said the Doctor, skidding on her knees to ram the glass with her fist. “Yaz! Hold on!” With her sonic, she superheated a section of the glass and kicked it in, shards of the panel collapsing to the floor in a sheet. Red lights and alarms started flashing and blaring, and the Doctor groped for Yaz’s wrist. Weak pulse. Still alive. The TARDIS shrilled at her, doors flying open. “I know, I know!” The Doctor scooped Yaz under the armpits and dragged her into the box, slamming the door behind her as a horde of hazmat nurses swarmed into the room.

“Keep them out for me, love, that’s good,” said the Doctor, laying Yaz by the stair. “Living sample, living sample, micro-nanochip… what am I _missing?”_ Fists banged on the TARDIS door. “Shove off a moment, I’m nearly there,” she shouted at them. “Living sample, self-destructing virus, living sample…”

Yaz was starting to shudder on the floor. “Don’t die on me, Yaz,” cried the Doctor, “I shan’t allow it.” She fell to her knees over her. But Yasmin Khan was dying in her arms. _No, we can’t have that. Can’t have a universe with no Yaz._ Bright, brave, brilliant Yasmin Khan, who always remembered to invite the Doctor for tea on drop-off days, who was the first to cross the boundary to Gallifrey, who tolerated the Doctor’s long speeches and sudden fancies and took on everything with an inherent curiosity, who suggested things like reversing the polarity on a mirror—

“Yaz! That’s it! Reverse the polarity! _Reverse!_ Reverse the _programming_ in the nanotech to fight itself!” The TARDIS trilled and the Doctor looked around frantically for a petri dish, anything to collect a sample. “Got to get a living sample, no time to rewire the self-destructing mechanism…” And it hit her. “I’d ask your consent first, ordinarily, but…” She pressed her mouth to Yaz’s, and she thought she could feel the virus tickling her lips as it spread into a new host.

Wasting no time, the Doctor dashed to the console, which produced a set of test tubes on its own. She waved the sonic over her own mouth, jamming the nanotech for a split second longer than it took to self-destruct, and spat into the tubes. “And a dash of Artron particles to boost the immune system…” The TARDIS retracted the test tubes into the console to process. A light flashed red; the virus had self-destructed.

The Doctor groaned. “Oh, I had just gotten that. No matter, plenty more where that came from. Did you get a scan on the tech?” The TARDIS blipped affirmative. “Well done. Now, let’s hack into that script, shall we?” Her fingers whizzed over a keyboard that flipped up from a panel. “Splash of code so the anti-virus doesn’t go rogue and start attacking cells… and… got it. How fast can you implement this?” The TARDIS buzzed. “I know you’re fast, but can you do it before it self-destructs?” Buzz. “Of _course_ , I’ll buy you more time, now are you ready?” Affirmative blip. “Good. Here it comes.” She drilled the sonic against her lips once more, holding it longer, and again spat into the test tubes.

“Come on, I know you can do it,” murmured the Doctor, watching the monitor as the TARDIS pushed the code into each nanochip of the millions of viruses that had reproduced already in the Doctor’s mouth. More hammering on the door. “Shut it,” she yelled at the staff outside. And the test tubes popped up with a chime, green light illuminating them from below. _Yes_.

She seized a vial full of clear fluid and ran back to Yaz. “Come on, Yaz, you can’t die. Can’t have a universe with no Yaz, I couldn’t bear it,” she said desperately, pouring some of the cure into her mouth. “Sorry it’s mostly my saliva. Not the worst thing you’ve drunk with me, though, is it?” The Doctor sipped a portion herself, dropping the empty tube with the tinkle of shattering glass. Tears started springing forward and she buried her face in Yaz’s shirt. “Come back to me, Yaz, you can’t leave like this. What’ll I tell Sonya and Najia and your dad? And Ryan and Graham? Don’t do this.”

“Don’t do what?” a faint, familiar voice answered. Gaping, the Doctor looked up into Yaz’s half-lidded eyes, peeking out at her. “Doctor, are you okay?”

“Oh, you,” gasped the Doctor into Yaz’s neck as she hugged her close. “You’ll be alright now. You’re alright.”

“Come again,” said Graham over the phone, set to speaker through the TARDIS console. “You went to alien planet Alpha-something and Yaz caught an incurable alien disease?”

“Alpha- _Seventeen_ , Graham,” the Doctor called over the other side of the console, craning her neck. “And it _was_ incurable, least ‘til I cured it.”

“I almost _died_ , Graham,” prodded Yaz, grinning at the Doctor with mischief in her eyes. The Doctor pursed her lips and lifted her eyebrows, a silent apology and guilty plea in one.

“You did not,” Ryan interjected.

“Yeah, she did,” the Doctor confirmed, “But luckily for her, I’m a doctor. Wasn’t gonna let that happen lying down.”

“Only had to contract the virus yourself, took you all of what, five seconds to cure yourself,” Yaz teased. “Me, I’m expendable.”

“Never.” The Doctor beamed.

“So, what happened to the other patient? Zero? And that bloke Nordoss?” asked Ryan.

“Nordoss won’t trouble a hospital again, I had his license revoked. He’ll be doing some hard time, if the mobs don’t find him first. I heard he ratted them out in court. Highly illegal on all fronts, bioweaponry.” The Doctor turned away so Yaz wouldn’t see her darkened expression. As soon as the other medical staff had confirmed that Yaz was in stable condition, the Doctor had cornered Nordoss, rage bubbling in her stomach like acid.

 _“I’ve called the local police. They’re to bring you in for questioning about certain illegal activities you’ve been conducting. Live experiments on humanoids_ and _a human.” She sneered at him as he started looking for exits. “Oh, mate. I wouldn’t try packing and running. I’ve already destroyed your work here. Constructed my own supervirus from the shell of yours to be stronger, faster, and smarter and eradicate any trace of what you created. There’s nothing left of yours here. ‘Cept maybe that dusty degree in your office.”_

“And we did cure Zero,” Yaz added. “He’s free to live his life how he chooses, mentioned something about going back to school to monitor the medical community. Guess this gave him a new passion.”

“Doc, we need to talk about how you’re handling Yaz without us around,” said Graham.

“Yeah, like she said, she could have _died_ ,” said Ryan.

“But that’s every day for us, innit?” countered Yaz.

“Your life isn’t up for debate here, Yaz, I’m just saying the Doc ought to mind you better…”

The Doctor smiled to herself. They had long since retired from Team TARDIS, but Ryan and Graham were still part of the fam. They hung up with the promise to meet in Sheffield the following Thursday.

“You did give me quite the scare,” said the Doctor, turning a crank on the console. “I’ll have to make a new rule that dying isn’t allowed on Team TARDIS. Not on my ship,” she added, enunciating every syllable.

“I’ll try harder to get out of the way next time an infected person comes barreling along, then,” said Yaz.

“I’m serious! I’m not exactly young, you know, nearly stopped both my hearts…”

“Not the way I wanted to do that.” Yaz sidled over and wrapped her arms around the Doctor’s waist from behind. “I didn’t say thank you properly, so… thanks. For not letting me die of an incurable alien disease.” She rested her chin on the Doctor’s shoulder and the Doctor rested her head against Yaz’s.

“Couldn’t have just let that happen,” said the Doctor softly.

“I’m glad you didn’t.”

The Doctor swallowed. They had been discharged from Alpha-Seventeen, allowed to convalesce aboard the TARDIS, who admonished them to take it easy. Yaz slowly returned to her normal self, with the side effect that the Doctor’s cure left sentient virus sentinels in their bodies: the antivirus would remain dormant until another virus threatened their health, which functionally made them both immune to most viruses. “Graham’s right, I’m too risky with you. I like a thrill every now and again, but this was too close a shave. And I don’t need to shave my face anymore!”

“But that’s a part of it. Traveling with you,” said Yaz.

“Right, well shaving’s a part of—”

“I meant almost dying.”

“Oh. Well still, it’s not allowed.”

“I’ll do my best." Yaz gave the Doctor another gentle squeeze and let go. "Sheffield, then?”

“Sheffield,” said the Doctor, and pulled the lever.

**Author's Note:**

> Hello again!
> 
> So I put out that request for prompts earlier, and someone answered! Thank you, anon tumblr friend! Is it too soon for a quarantine fic? You be the judge of that. I had a LOT of fun writing this one, and did so after way too much coffee. I'm quite tired.
> 
> Smash any buttons you like, comments make me super happy, wash your hands, and remember to be kind to yourselves!
> 
> Cheers,  
> Jo


End file.
